I think you could use Nomex paper for insulating the panel from the ground board trace as an easy solution ( or you can use Furio's acrylic panels).
Thanks a lot for sharing all your experiments with this VCO board, this threat is getting hot.

As i already have a alu panel i really like, i might try fitting some Nomex or similar in there.
Theres not much room, but ill see what i can do. Ill let you guys know if it helps.

Im still a bit mesmerized, about how it can work on the original and not with this. The original grounds thru the panel as well after all..

The common ground in the case or panel wouldn't be a problem if you get separate ground traces for each oscillator avoiding the ground loop between them,(only common point in the power conector).

Sure, but avoiding that connection thru the panel is pretty impossible imo. Pots are mounted on the panel, as are jacks. Even if we do manage to insulate them somehow, i bet some would leak thru anyway.. Must be a better and more simple way to sort this out. Would really like to know the real reason for this issue happening..

You don´t need to insulate the board from panel.
You need create a GND trace from power connector through oscillator 1 to chasis and other from power conector through oscillator 2 to chasis.
Original Arp VCOs are built in different boards so this issue doesn't occurs.

You don´t need to insulate the board from panel.
You need create a GND trace from power connector through oscillator 1 to chasis and other from power conector through oscillator 2 to chasis.
Original Arp VCOs are built in different boards so this issue doesn't occurs.

Mine are on different boards actually. Both with their own Ground trace obviously. But as panels are touching, they share Ground. (considering they are out of metal that is, which mine are)

I see...
Sync in jack socket seems to be the problem.
did you try to dismount them from panel?
(offtopic: what software was used for creating the VCO layouts? I like the components view more than eagle.)

I see...
Sync in jack socket seems to be the problem.
did you try to dismount them from panel?
(offtopic: what software was used for creating the VCO layouts? I like the components view more than eagle.)

My VCO's Sync points are hardwired, but yea, that might be it. Gonna test this when i service my pair in a bit.

If the sync GND jack is the problem then I have a simple isolating solution.
Do you know the Teflon paper roll?
It's thin, white and comes in a small round package.
You can just roll some on the jack and then put it in the panel.
Tell me if it helped _________________http://www.myspace.com/mgmtrance

Let me get this straight...
Sync on/off is turned on with a toggle switch, right?
The problem happanes is when the synch is off cause the toggle switch body is grounded with other pots/jacks on the front panel, right?
Assuming that what I understand is correct ...put teflon paper on the toggle it self.
Or I'm totally out of direction and I really don't know what your talking about _________________http://www.myspace.com/mgmtrance

Let me get this straight...
Sync on/off is turned on with a toggle switch, right?
The problem happanes is when the synch is off cause the toggle switch body is grounded with other pots/jacks on the front panel, right?
Assuming that what I understand is correct ...put teflon paper on the toggle it self.
Or I'm totally out of direction and I really don't know what your talking about

Yep, you got it right. Lets hope this is the problem, then its fixable. Ill let you know when ive tested it..

Let me get this straight...
Sync on/off is turned on with a toggle switch, right?
The problem happanes is when the synch is off cause the toggle switch body is grounded with other pots/jacks on the front panel, right?
Assuming that what I understand is correct ...put teflon paper on the toggle it self.
Or I'm totally out of direction and I really don't know what your talking about

Yep, you got it right. Lets hope this is the problem, then its fixable. Ill let you know when ive tested it..

waiting for success ....
A picture of my boards.
I want to use some of them as LFVCO changing the cv1 input jumper for a toggle switch to 270K resistor. I see Furio's panels don´t include this socket but I think it is interesting too in this single version. Do you think there is enough space for add a socket for a miniature toggle switch in your panel?.

Had a minute free, so i detached the sync-switch and tried. Same issue happens.
However, as i dont have the real Odyssey here, i compared my results to the Oddity VSTi, and its behaving pretty similar.
Tho, the VCO's do phase each other out a lot more when tuned together/close than the Oddity does.
As they are analog, they should have different cycles, but they seem to share the same cycle each time i turn it on.

I used some crappy trannies when i did my VCO's tho, so ill see how it behaves when replaced by quality ones i have here waiting..

Had some time over, so i went ahead and replaced all my 3904/3906's. Used some fishy ones, and the new ones are quality trusted ones from Mouser. Also made a Ground-chain between the pots on each section while i had it opened.

The Ground-chain didnt do much difference i think, but the new trannies made a lot of difference! Improved sound, MUCH lower pitch, and a lot less locking. They still lock together a bit, but the original does this too i hear.

I have also been informed on the reason behind this, and the fix is to put a 100nF cap after the 10uF caps.
The 100nF might be filtering too much, or too little, so one can decide for one self here.
Ill see if i do this at some point, it would need some hacking on this layout.

Hi everyone,
I have just finished to scketch the PCB of the Ring Modulator (version for 'Erthenvar' jacks).
If someone would like to help me check it, here is the preview ... The 150K Input2 is to be soldered on the side of the tracks .... The 5K6 and 100n capacitor can be soldered inbetween the socket in the middle/under of the CD4011. The euro power connector must be angled.

I have built this VCO and works fine but I hear some change in the PW when I turn the PWM potentiometer but nothing is connected in the PWM jack. This is ok? I think the PW shouldn't change turning the PWM pot with nothing in the input.

I have built this VCO and works fine but I hear some change in the PW when I turn the PWM potentiometer but nothing is connected in the PWM jack. This is ok? I think the PW shouldn't change turning the PWM pot with nothing in the input.

This is normal. Without connecting anything, the potentiometers FM and PWM must be completely in the CCW position.

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